Controller for circuit interrupters



y 23, 1939- c. STANSBURY 2,159,298

CONTROLLER FOR CIRCUIT INTERRUPTERS Filed Oct. 9, 1936.

Patented May 23, 1939 CONTROLLER. FOR, CIRCUIT INTERRUPTERS Carroll Stansbury, Wauwatosa, Wis., assignor to Cutler-Hammer, Inc., Milwaukee, Wis., a corporation of Delaware Application October 9, 1936, Serial No. 104,749

16 Claims. (Cl. 175-294) This invention relates to a method and means for controlling an arc rupturing switch interposed in an alternating current circuit in such a manner that substantially no opening arc is produced at the switch contacts.

. An object of the invention is to provide a system for repeatedly opening and closing an alternating work circuit in such a manner that arcing at the circuit opening contacts is reduced to a 1 minimum.

Another object is to provide for the correction of the action of circuit breaking contacts resulting from wear incident upon repeated operation.

Another object is to provide sensitive means for measuring the voltage obtaining between contacts at the instant of their separation and adjust the moment of separation so as to reduce said voltage to a minimum.

Another object is to provide a system and method for causing alternating current flow to a translating device for a measured interval and time the beginning of said interval so that the voltage of the end of said interval is a minimum.

Other objects and advantages will hereinafter appear.

The accompanying drawing is illustrative of two systems embodying my invention.

In the drawing:

Figure 1 is a system in which the current to a translating device is controlled-by means of an electronic tube timer, while Fig. 2 illustrates a system wherein the current is controlled by a mechanical timer, driven by a synchronous motor.

Referring to Fig. 1, an electromagnetic switch I, having an energizing winding l and a movable bridging contact l which is adapted to bridge the stationary contacts I and I controls the supply of current to the primary winding 2 of a transformer 2. Said transformer also has a secondary winding 2 which may supply the electrodes of an electric welder. Energy is supplied from the terminals L L and L of a polyphase circuit. The system further. includes a pilot switch 3, having a movable contact 3 which normally makes contact with the stationary contact 3 and which may be operated to alternatively make contact with stationary contact 3. A rectifier 4 which may be of any known type has a cathode and" an anode 4 When the switch 3 is in its normal position it connects a condenser 5 in series with rectifier 4 and a resistor 6 across the terminals L and L Connected between the terminal L and contact 3 is the coil I"- in series with the cathode l and anode l of a gaseous electronic tube '2 which is also provided with a control grid F. A battery 8 connected in series with resistors 9 and I0 between the cathode I and grid 1 provides a normally negative bias for said grid. Connected to the lines L L and L is the primary winding ll of an induction regulator ll, having a rotating secondary winding ll By rotating said secondary winding the phase of the voltage induced therein relative to the phase of the Supply voltage may be regulated. A gaseous discharge tube I2 is connected in series with a resistance l3 across the terminals of said secondary winding. Resistor 9 is also connected in series with a condenser l4 across the terminals of tube l2.

Coupled to the secondary winding II and revolving therewith is a ratchet wheel I5 which may be moved in opposite directions by the pawls IB and ll, respectively. The pawls I6 and I1 may be operated by electromagnetic windings l8 and I9, respectively. Said electromagnets are connected in series with three-element electron tubes 20 and 2|, respectively, across the terminals of a battery 22. Another battery 23 supplies normally a negative bias to the grids of said tubes through limiting resistors 24 and 25, respectively. A condenser 26 is connected between the grids, and one terminal thereof is also connected through an adjustable resistor 21 to line L and contact 1, while the otherterminal is connected to contact l The system operates as follows: With the pilot switch 3 in the positon shown the condenser 5 stores up a given amount of electrical energy. If the pilot switch is now operated, the condenser is connected in a discharge circuit including the coil I" and tube 1. However, the potential of grid 1 is such that no discharge current can flow, until tube [2 discharges at a given moment in the cycle of the alternating current, whereupon a positive potential is superposed upon the potential from battery 8 and the tube 1 becomes conducting, permitting the condenser to dischargethrough coil .l' and maintaining the magnet energized and closing circuit between contacts I and I for a time interval which depends on the design of the circuit constants. The operation of this part of the equipment is more fully explained in my co-pending application, Serial No. 100,279, filed September 11, 1936. Closure of contacts by switch I energizes the transformer 2 and supplies welding current.

It will be noted that the switch i is closed for a given interval and that the beginning of said interval relative to the time phase of the alternating welding current is determined by the moment at which tube 1 becomes conducting. Hence the time phase of opening said circuit is also dependent on the moment of its closure. In order to prevent excessive wear of the contacts of switch I due to the opening are it is desirable to open the switch when the voltage is zero, i. e., when there is no arcing; This is accomplished as follows: Assume that an arc appears on separating the contacts I and W. The polarity of said are will be positive or negative depending on whether the circuit is opened before or after the completion of the positive half cycle of the alternating current. A unidirectional voltage is thus impressed on condenser 26, of a magnitude depending on the polarity and magnitude of the are This voltage is superposed on the bias cuit. On the succeeding operation of the switch.

I the moment of opening and closing will therefore be retarded or advanced, depending on the correction made and thus the opening arc is reduced or eliminated.

If the total time during which switch 0 is energlzed is modified by adjusting condenser ii, the correction aforedescribed will immediately take place to produce the desired result.

In Fig. 2 the switch contacts are operated by a cam 30 which in turn is rotated through a reduction gearing M by a synchronous motor 32, having a rotatable armature 32 and a rotatable field 32. The latter may be rotated in opposite directions by the worm 33 which is driven by a reversing motor M, having reversing fields M and 34' respectively.

When an arc appears between the contacts [1 and l one of the magnets it or 09 is energized, thereby energizing the motor through the fields 34* or M by closure of their respective contacts it! or til Thereupon the field 32 is rotated in one or the other direction and this causes retardation or advance of the time phase of operating the contacts i and l in the manner aforedescribed.

It is to be understood that the cam 363 may be made adjustable so as to vary the relative time during which the switch is open or closed. Also any other actuating mechanism may be inter-= posed between the driving motor and the switch.

What 'Iclairn as new and desire to secure by Letters Patent is: r

1. In a controller for an alternating current circuit, the combination with a power-operated switch controlling the continuity of said circuit, of means to effect cyclic closing and opening of said switch, and means to effect opening of said switch by said first mentioned means in a substantially constant time-phase relation to the time-phaseof the controlled circuit, said last mentioned means including means operable as a function of arcing between the switch contacts.

2. In a controller for an alternating current circuit, the combination with a power-operated switch controlling the continuity or said circuit,

aicaaoa of means to efiect closing and opening of said switch cyclically, and means to effect opening of said switch by the former means in a substantially constant time-phase relation to the time-phase of the controlled circuit, said last mentioned means including energy storage means operable as a function of arcing between the switch contacts.

3. In a controller for an alternating current circuit, the combination with a power-operated switch controlling the continuity of said circuit, of electromagnetic means to effect closing and opening of said switch cyclically, and means to effect opening of said switch by the former means in a substantially constant time-phase relation to the time-phase of the controlled circuit, said last mentioned means including means operable as a function of arcing between the switch contacts.

4. In a controller for an alternating current circuit, the combination with a power-operated switch, of electromagnetic means to effect closing and opening of said switch cyclically, and means to efiect opening of said switch by the former means in a substantially constant timephase relation to the time phase of the controlled circuit, said last mentioned means including energy storage means operable as a function of arcing between the switch contacts.

5. In a controller for an alternating current circuit, the combination with a power-operated switch controlling the continuity of said circuit,

of electromagnetic means to effect closing and opening of said switch cyclically, and means to effect opening of said switch by the former means in a substantially constant time-phase relation to the time-phase of the controlled circuit, said last mentioned means including electronic means operable as a function of arcing between the switch contacts.

6. In a controller for an alternating current circuit, the combination with a power-operated switch controlling the continuity of said circuit, of electromagnetic means to effect closing and opening or" said switch cyclically, and means effecting opening of said switch by the former means in a substantially constant time-phase relation to the time-phase oi the controlled circuit, said last mentioned means including electronic tube means operable as a function of arc ing between the switch contacts and electromagnetic reversing means under the control of said electronic tube means to influence said electromagnetic means.

7. In a controller for an alternating current circuit, the combination with a power-operated switch controlling the continuity of said circuit, of means to effect closing and opening of said switch cyclically, and means to efiect opening of said switch by the former means in a substantially constant time-phase relation to the timephase of the controlled circuit, said last mentioned means including energy storage means operable as a function of arcing between the switch contacts, electronic tube means under the control of said energy storage means, and electromagnetic reversing means controlled by said electronic tube means and influencing said first mentioned means.

8. In a controller for an alternating current circuit, the combination with a power-operated switch controlling the continuity of said circuit, of electromagnetic means to efiect closing and opening of said switch cyclically and having an energizing coil, and means effecting opening of said switch by said electromagnetic means in a substantially constant time-phase relation to the time-phase of the controlled circuit, said last mentioned means including electronic tube means -energizing coil, and means effecting opening of said switch by the former means in a substantially constant time-phase relation to the timephase of the controlled circuit, said last mentioned means including energy storage means operable as a function of arcing between the switch contacts, electronic tube means under control of said energy storage means and electromagnetic reversing means controlled by said electronic tube means and influencing said energizing coil.

10. In a controller for an alternating current circuit, the combination with a power-operated switch controlling the continuity of said circuit, of electromagnetic means to effect closing and opening of said switch and having an energizing coil, means including a grid type electron tube connected in circuit with said coil and a source of energy to energize said coil cyclically, and means connected to the alternating current circuit and to said grid to control the conductivity of said tube for controlling said coil to effect opening of said switch in a substantially constant 'time-phase relation to the time-phase of the controlled circuit, said last mentioned means including energy storage means operable as a function of arcing between the switch contacts and electronic tube means under the control of such energy storage means and influencing said grid control means.

11. In a controller for an alternating current circuit, the combination with a power-operated switch controlling the continuity of said circuit, of a synchronous motor having an armature and a relatively stationary field structure, said motor effecting closing and opening of said switch cyclically, and means to effect opening of said switch by said motor in a substantially constant time-phase relation to the time-phase of the controlled circuit, said last mentioned means including means operable as a function of arcing between the switch contacts to effect rotations of said field structure.

12. In a controller for an alternating current circuit, the combination with a power-operated switch controlling the continuity of said circuit, of a synchronous motor having an armature and a relatively stationary field structure, said motor effecting closing and opening of said switch cyclically, and means to effect opening of said switch by said motor in a substantially constant time-phase relation to the time-phase of the controlled circuit, said last mentioned means including energy storage means operable as a function of arcing between the switch contacts to effect rotation of said field structure.

13. In a controller for an alternating current circuit, the combination with a power-operated switch controlling the continuity of said circuit, of a synchronous motor having an armature and a relatively stationary field structure, said motor effecting closing and opening of said switch cyclically, and means to effect opening of said switch by said motor in a substantially constant time-phase relation to the time-phase of the controlled circuit, said last mentioned means including energy storage means operable as a function of arcing between the switch contacts and electronic tube means under the control of said energy storage means and adapted to effect A time-phase. relation to the time-phase of the controlled circuit, said last mentioned means including energy storage means operable as a function of arcing between the switch contacts, electronictube means under the control of said energy storage means and electromagnetic reversing means controlled by said electronic tube means and effecting rotation of said field structure.

15. In the method of controlling a cyclic operating force effecting the repeated operation of contacts for interrupting the flow of an alternating current with a minimum of arcing at said contacts the steps of adjusting the time phase of said cyclic operating force relative to the time-phase of the alternating current, determining the polarity and magnitude of any are which may occur from the opening of the contacts and using the result of such determination to modify the time-phase of said cyclic operating force.

16. In a controller for an alternating current circuit, the combination with a power operated switch controlling the continuity of said circuit, of means to effect cyclic closing and opening of said switch, and means responsive to variations in the time phase of the energy flowing in said circuit relative to the time of opening of said switch to effect adjustment of the moment of opening of said switch by said first mentioned means, whereby arcing oi! said switch is reduced to a minimum,

CARROLL STANSBURY. 

